USB接口（2）——USB控制器EHCI、OHCI、UHCI与usb hub芯片

大家好，欢迎来到IT知识分享网。

EHCI和OHCI,UHCI概念

USB控制器类型：

OHCI、UHCI都是USB1.1的接口标准，而EHCI是对应USB2.0的接口标准，最新的xHCI是USB3.0的接口标准。

OHCI( Open Host Controller Interface ) ：一个不仅仅是usb用的主控制器接口标准。主要是遵循csr (configuration space register)标准。是其他厂商在设计usb host controller时遵循的标准，如via, nec, ali, 包括nvidia等等。支持USB1.1的标准。

UHCI (Universal Host Controller Interface )，是Intel主导的对USB1.0、1.1的接口标准，与OHCI不兼容。

EHCI(Enhanced Host Controller Interface ) ，是Intel主导的USB2.0的接口标准。EHCI仅提供USB2.0的高速功能，而依靠UHCI或OHCI来提供对全速(full-speed)或低速(low-speed)设备的支持。

usb hub

USB Hub可以将一个USB口转换为多个，USB Host带有Root Hub，第一个USB设备是一个根集线器(Root_hub)，它控制连接到其上的整个USB总线，该控制器是连接PCI总线和USB总线的桥，也是该总线上的第一个USB设备，USB Hub对于上游而言是一个USB Device, 对于下游而言扮演USB Host, 所以USB设备本身不知道自己连接在Hub还是Root Hub上。

EHCI和OHCI host Controller初始化

rk3399平台

rk3399平台host Controller初始化信息

[ 2.] ehci-platform fe.usb: EHCI Host Controller [ 2.] ehci-platform fe.usb: new USB bus registered, assigned bus number 4 [ 2.] ehci-platform fe.usb: irq 28, io mem 0xfe [ 2.] ehci-platform fe.usb: USB 2.0 started, EHCI 1.00 [ 2.] usb usb4: New USB device found, idVendor=1d6b, idProduct=0002 [ 2.] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1 [ 2.] usb usb4: Product: EHCI Host Controller [ 2.] usb usb4: Manufacturer: Linux 4.4.189 ehci_hcd [ 2.] usb usb4: SerialNumber: fe.usb [ 2.] hub 4-0:1.0: USB hub found [ 2.] hub 4-0:1.0: 1 port detected [ 2.] ohci-platform fe3a0000.usb: Generic Platform OHCI controller [ 2.] ohci-platform fe3a0000.usb: new USB bus registered, assigned bus number 3 [ 2.] ohci-platform fe3a0000.usb: irq 29, io mem 0xfe3a0000 [ 2.] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001 [ 2.] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1 [ 2.] usb usb3: Product: Generic Platform OHCI controller [ 2.] usb usb3: Manufacturer: Linux 4.4.189 ohci_hcd [ 2.] usb usb3: SerialNumber: fe3a0000.usb [ 2.] hub 3-0:1.0: USB hub found [ 2.] hub 3-0:1.0: 1 port detected 

经由usb hub扩展，鼠标设备（低速设备）的加载信息，鼠标连接到ehci控制器上面。

[root@rk3399:/]# [ 69.] usb 3-1.1: new low-speed USB device number 4 using ehci-platform [ 69.] usb 3-1.1: New USB device found, idVendor=046d, idProduct=c05a 

不经usb hub扩展，鼠标设备（低速设备）的加载信息，鼠标连接到ohci控制器上面。

[root@rk3399:/]# [ 16.] usb 3-1: new low-speed USB device number 2 using ohci-platform [ 16.] usb 3-1: New USB device found, idVendor=046d, idProduct=c05a 

无论是否经usb hub扩展，U盘设备（高速设备）的加载信息，U盘连接到ehci控制器上面。

[root@rk3399:/]# [ 6315.] usb 4-1: new high-speed USB device number 3 using ehci-platform [ 6316.062160] usb 4-1: New USB device found, idVendor=05e3, idProduct=0749 

理论上，EHCI仅提供USB2.0的高速功能，要依靠UHCI或OHCI来提供对全速(full-speed)或低速(low-speed)设备的支持。鼠标设备这样的低速设备应该连接到UHCI或OHCI控制器上，但是经由usb hub，鼠标也可以连接到EHCI控制器上。所以，usb hub是可以将不同速度的设备都连接到EHCI控制器上的，具有匹配不同速度设备的能力。

xx18平台

内核usb host接口相关文件 ./arch/arm/mach-s5p4418/include/mach/usb-phy.h ./arch/arm/mach-s5p4418/soc/setup-usb-phy.c ./drivers/usb/host/ehci.h ./drivers/usb/host/ehci-hcd.c ./drivers/usb/host/ehci-synop.c ./drivers/usb/host/ohci.h ./drivers/usb/host/ohci-hcd.c ./drivers/usb/host/ohci-synop.c 

INCR16 INCR8 INCR4 0xC002_0000 OHCI Controller 0xC003_0000 EHCI Controller 

xx18平台USB host Controller初始化信息，默认xx18平台只配置了EHCI，OHCI没有配置：

[ 2.050000] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver [ 2.057000] nxp-ehci nxp-ehci: SLsi Synopsys EHCI Host Controller [ 2.063000] nxp-ehci nxp-ehci: new USB bus registered, assigned bus number 1 [ 2.070000] nxp-ehci nxp-ehci: irq 50, io mem 0xc0030000 [ 2.082000] nxp-ehci nxp-ehci: USB 0.0 started, EHCI 1.00 [ 2.087000] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002 [ 2.094000] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1 [ 2.] usb usb1: Product: SLsi Synopsys EHCI Host Controller [ 2.] usb usb1: Manufacturer: Linux 3.4.39 ehci_hcd [ 2.] usb usb1: SerialNumber: nxp-ehci [ 2.] hub 1-0:1.0: USB hub found [ 2.] hub 1-0:1.0: 3 ports detected 

若要添加对OHCI的支持，我们需要将内核中OHCI相关配置打开，如下：

--- a/linux/kernel/kernel-3.4.39/arch/arm/configs/s5p6818_linux_forlinx_defconfig +++ b/linux/kernel/kernel-3.4.39/arch/arm/configs/s5p6818_linux_forlinx_defconfig @@ -2465,8 +2465,13 @@ CONFIG_USB_EHCI_SYNOPSYS_RESUME_WORK=y # CONFIG_USB_ISP116X_HCD is not set # CONFIG_USB_ISP1760_HCD is not set # CONFIG_USB_ISP1362_HCD is not set -# CONFIG_USB_OHCI_HCD is not set +CONFIG_USB_OHCI_HCD=y +CONFIG_USB_OHCI_SYNOPSYS=y +# CONFIG_USB_OHCI_HCD_PLATFORM is not set # CONFIG_USB_EHCI_HCD_PLATFORM is not set +# CONFIG_USB_OHCI_BIG_ENDIAN_DESC is not set +# CONFIG_USB_OHCI_BIG_ENDIAN_MMIO is not set +CONFIG_USB_OHCI_LITTLE_ENDIAN=y # CONFIG_USB_SL811_HCD is not set # CONFIG_USB_R8A66597_HCD is not set CONFIG_USB_DWCOTG=y 

打开配置以后，OHCI初始化信息：

[ 2.] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver [ 2.] nxp-ohci nxp-ohci: SLsi Synopsys OHCI Host Controller [ 2.] nxp-ohci nxp-ohci: new USB bus registered, assigned bus number 3 [ 2.] nxp-ohci nxp-ohci: irq 50, io mem 0xc0020000 [ 2.] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001 [ 2.] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1 [ 2.] usb usb3: Product: SLsi Synopsys OHCI Host Controller [ 2.] usb usb3: Manufacturer: Linux 3.4.39 ohci_hcd [ 2.] usb usb3: SerialNumber: nxp-ohci [ 2.] hub 3-0:1.0: USB hub found [ 2.] hub 3-0:1.0: 3 ports detected